How to install an expansion pack?

To Install Expansion Packs you first should make sure you're running the very latest version of FrameForge

Run FrameForge as you would normally.
Go to the Help Menu and click Check for Program Updates.
If will either tell you the program is up-to-date in which case you can cancel out of the Updater, otherwise, if it displays a list of checked files, then have it install any files it suggests.

Once you know the program is up-to-date, launch FrameForge.

From within FrameForge, click on the Tools Menu.
Click on the Menu item Install Expansion Pack.
The standard Open File Dialog will appear and you should select the Expansion Pack's Installation file which will either have the extension .CPACK or CPACK3.
It will prompt you for the Expansion Pack's Serial Number which is not your FrameForge 3D Studio Serial Number but which you will have received which you purchased the pack.
Enter this serial number and the Expansion Pack, including all objects, textures, sets, poses and relationships will be installed for you.